2.519 Error ModManager.cpp:1782: Error while loading item prototype "crushed-coal" (item): ItemPrototype::fuel_category was removed. Please use ItemPrototype::fuel_categories.
Modifications: Crushing Industry

Hi, yep this is a known issue, I'll update for the new version Soon™

Is there a fix I can implement locally in the mean time?

For other mods, the tempfix is changing any instance of fuel_category = "thing" to fuel_categories = {"thing"}. Won't work if mods combine categories or are doing anything fancy, but should work for mods that are just targeting "chemical".

Either way, fixed with 0.6.8! Others following shortly.